Implement BOTW save data mounting

- Add account initialization and user handling
- Mount save data using BOTW Application ID
- Proper error handling with Result codes
- Foundation for save file manipulation

source/save_basic.c

@@ -6,11 +6,38 @@
 static gameDataSav save_data = {0};
 
 void openSave() {
+    Result rc = 0;
+    AccountUid uid = {0};
+    u64 application_id = 0x01007ef00011e000; // BOTW Application ID
+    
     printf("Opening BOTW save data...\n");
-    // TODO: Implement save file reading
+    
+    // Get user account
+    rc = accountInitialize(AccountServiceType_Application);
+    if (R_FAILED(rc)) {
+        printf("accountInitialize() failed: 0x%x\n", rc);
+        return;
+    }
+    
+    rc = accountGetPreselectedUser(&uid);
+    accountExit();
+    
+    if (R_FAILED(rc)) {
+        printf("accountGetPreselectedUser() failed: 0x%x\n", rc);
+        return;
+    }
+    
+    // Mount save data
+    rc = fsdevMountSaveData("save", application_id, uid);
+    if (R_FAILED(rc)) {
+        printf("fsdevMountSaveData() failed: 0x%x\n", rc);
+        return;
+    }
+    
+    printf("Save data mounted successfully!\n");
 }
 
 void processSave() {
     printf("Processing save data...\n");
-    // TODO: Implement save processing logic
+    // TODO: Implement actual save processing
 }